NOx Emissions from Cement Mfg - US Environmental Protection ...

The annualized costs expected for urea-based SNCR systems
are given in Table 6-11 and include operating labor costs,
maintenance and overhead costs, and the indirect operating costs.
The urea reagent costs were estimated assuming 50 percent NOx
removal efficiency, 35 percent reagent utilization, and 80 cents
per gallon of 50 percent reagent solution.16 Because in an SNCR
process, an aqueous solution of the urea- or ammonia-based
reducing agents is used along with cooler carrier air or steam,
there will be a certain loss of heat from the kiln gases. The
associated energy penalty is assumed to be 0.3 percent of the
kiln fuel costs. Because coal is the most predominant fuel used
in cement kilns, the fuel costs are assumed to be approximately
$2.5/MM Btu. The total annualized costs for the four model
plants varied significantly, due to different levels of annual
NOx emissions. The estimated annualized costs range from a low
of about $438,000/yr for the small preheater kiln to a high of
$820,000/yr for the large precalciner kiln.
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